Wayback Machine - Browse through over 150 billion web pages archived from 1996 to a few months ago.
Waybackpack - Download the entire Wayback Machine archive for a given URL
ArchiveBox - The open-source, self-hosted internet archiving solution
Archive.md - archive.is allows you to create a copy of a webpage that will always be up even if the original link is down
Every Second - Realtime stats per second of Apple and YouTube
Brunhilde - Analyze YouTube comments to know what your audience thinks